1. Field of the Invention
The present invention relates to a relay server and more specifically to a relay server that enables communication to be performed between terminals connected to different LANs (Local Area Networks).
2. Description of the Related Art
Conventionally, a communication technology called a virtual private network (Virtual Private Network, VPN) has been known (for example, see Japanese Patent Application Laid-Open No. 2002-217938). The VPN is used for, for example, performing communication via Internet between terminals that are connected to LANs of a plurality of branch offices (stations) each located in each regions. Use of the VPN enables another LAN located in a distant place to be used as if it is a directly-connected network.
In this type of system, a configuration is known in which a relay server stores, not only identification information and an IP address of a terminal within a LAN to which the relay server itself is connected, but also identification information and an IP address of a terminal that is connected to another LAN, and performs communication based on a content thus stored. In this configuration, in a case where a large number of terminals are connected to each LAN, the relay server stores an enormous amount of information. Additionally, in this configuration, in a case where terminals connected to the LANs are frequently changed, the relay servers have to exchange information each time a change occurs. This makes the process troublesome, and causes an enormous amount of information to be exchanged between the relay servers.